In recent years, standardization, test installation for various usages, and the like of RFID (Radio Frequency IDentification) tags (also referred to as ID tags, IC tags, wireless tags, or wireless chips) have started so that RFID tags can be put into practical use. RFID tags have a feature in communication range, used protocol, and the like in accordance with a used frequency band and have a great advantage that non-contact response is possible in any frequency band. With such convenience, RFID tags are expected to be used in various fields such as personal authentication, fare payment, and games (refer to, for example, Patent Document 1: Japanese Published Patent Application No. 2002-56171).
In the current authentication systems using a cash card, a membership card, and the like, in general, an account number or a membership number stored in the card and a personal identification number are used to correspond to one of a plurality of pieces of personal data stored in the server. In these systems, a cash card and a membership card which a user possesses are a key for calling up personal data stored in the server. Further, as a measure for security, entry of a personal identification number or the like is also employed in many cases.
In other words, for example, even when a third person will pick up a card and try to illegally use the card, authentication is not achieved unless the third person obtains both the card and the personal identification number. Therefore, the above system has been used for a long time and is noted as one of the main personal authentication systems.